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  • should I use Entity Framework instead of raw ADO.NET

    - by user110182
    I am new to CSLA and Entity Framework. I am creating a new CSLA / Silverlight application that will replace a 12 year old Win32 C++ system. The old system uses a custom DCOM business object library and uses ODBC to get to SQL Server. The new system will not immediately replace the old system -- they must coexist against the same database for years to come. At first I thought EF was the way to go since it is the latest and greatest. After making a small EF model and only 2 CSLA editable root objects (I will eventually have hundreds of objects as my DB has 800+ tables) I am seriously questioning the use of EF. In the current system I have the need many times to do fine detail performance tuning of the queries which I can do because of 100% control of generated SQL. But it seems in EF that so much happens behind the scenes that I lose that control. Article like http://toomanylayers.blogspot.com/2009/01/entity-framework-and-linq-to-sql.html don't help my impression of EF. People seem to like EF because of LINQ to EF but since my criteria is passed between client and server as criteria object it seems like I could build queries just as easily without LINQ. I understand in WCF RIA that there is query projection (or something like that) where I can do client side LINQ which does move to the server before translation into actual SQL so in that case I can see the benefit of EF, but not in CSLA. If I use raw ADO.NET, will I regret my decision 5 years from now? Has anyone else made this choice recently and which way did you go?

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  • Migrating complex SVN branch hierarchy to Mercurial

    - by Christian Hang
    Our team has been using SVN for managing an application of decent size and over time a rather complex hierarchy of branches and tags has built up, which is following the basic standard layout for SVN repositories, but is more nested: |-trunk |-branches | |-releases | | |-releaseA | | `-releaseB | `-features | |-featureX | `-featureY |-tags |-releaseA | |-beta | `-RTP `-releaseB |-beta `-RTP (The feature branches are obviously temporary branches but we have to take them into consideration as it won't be feasible to close all of them at once in the near future) For several reasons but primarily because merges have been becoming an increasing pain, we are considering to switch to Mercurial. The main problem we are currently facing is migrating the existing code base without losing our history. I've tried several migration tools (e.g., yasvn2hg, hg convert and svn2hg) with yasvn2hg being the most promising, but none of them seem to be able to deal with nested hierarchies but they all assume that branches and tags are organized in one flat directory respectively. The choice between named branches or clones as the conversion target of old SVN branches is not a limiting factor in this case, as either solution would be appreciated. We are currently experimenting with both options and how they would fit into our current processes but haven't decided on one yet. I'd obviously be interested in recommendations or experiences with similar setups concerning that issue as well. So, what is the best way to convert a nested SVN branch hierarchy like this to Mercurial? Converting one branch at a time into a separate repository would be quite annoying and I am not sure if that would be the right approach in the first place, depending on how the tools handle historic merges and need to be aware of all other branches?

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  • AVFoundation: Video to OpenGL texture working - How to play and sync audio?

    - by j00hi
    I've managed to load a video-track of a movie frame by frame into a OpenGL texture with AVFoundation. I followed the steps described in the answer here: iOS4: how do I use video file as an OpenGL texture? and took some code from the GLVideoFrame sample from WWDC2010 which can be downloaded here: http://bit.ly/cEf0rM How do I play the audio-track of the movie synchronously to the video. I think it would not be a good idea to play it in a separate player, but to use the audio-track of the same AVAsset. AVAssetTrack* audioTrack = [[asset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0]; I retrieve a videoframe and it's timestamp in the CADisplayLink-callback via CMSampleBufferRef sampleBuffer = [self.readerOutput copyNextSampleBuffer]; CMTime timestamp = CMSampleBufferGetPresentationTimeStamp( sampleBuffer ); where readerOutput is of type AVAssetReaderTrackOutput* How to get the corresponding audio-samples? And how to play them? Edit: I've looked around a bit and I think, best would be to use AudioQueue from the AudioToolbox.framework using the approach described here: AVAssetReader and Audio Queue streaming problem There is also an audio-player in the AVFoundation: AVAudioPlayer. But I don't know exactly how I should pass data to it's initWithData-initializer which expects NSData. Furthermore I don't think it's the best choice for my case because a new AVAudioPlayer-instance would have to be created for every new chunk of audio samples, as I understand it. Any other suggestions? What's the best way to play the raw audio samples which i get from the AVAssetReaderTrackOutput?

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  • iPhone TableView alternative options for Check Mark Accessory

    - by jimsis
    I'm looking for the best approach to this problem. In my tableview I have a list of options from which you can select one and only one. The problem is the selection to choose is not obvious without displaying more details on the option. If I use the disclosure indicator or button for the more detail, I lose the checkmark functionality. In searching around I see some have used the cell Image as a work around. I see others instead of using the standard disclosure button have created custom disclosure button looking like a checkmark. Haven't seen this one but is it viable (HIG) to add a button in the cell ('more info') to launch the next tableview. My thought was to use a disclosure indicator and on the second view in the navigation bar (where the edit button usually is) add a 'selectMe' button. I think I am probably manage to code either of the above, am just asking for information on what is the best (HIG) way. Example Option 1 Option 2 Option 3 (x) Option 4 Where x is the checked one But in order to know which is the best choice you need to see Option 3 (Header) Option 3-a Option 3-b Option 3-c Option 3-d Where even at this level option 3-c might have additional information. Any guidance you can provide would appreciated.

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  • Facebook multi-friend-selector + new javascript API = BROKEN ?

    - by Simon_Weaver
    I am using the fb:serverfbml tag to render a multi-friend-selector inside an IFrame. I am using the new javascript API. I have been trying ALL DAY to get it working. When I click on the underlines 'selected' link (to filter by the selected friends) the whole page refreshes and the selected friends disappear. Does the multi-friend-selector just not work with the javascript API? <fb:serverfbml> <script type="text/fbml"> <fb:request-form action="http://apps.facebook.com/rollingrazor/" target="_top" method="POST" invite="true" type="Blah blah blah" content="Blah blah! &lt;fb:req-choice url=&quot;http://apps.facebook.com/rollingrazor/&quot; label=&quot;Let me check my friends&quot; /&gt;"> <fb:multi-friend-selector showborder="false" actiontext="Invite your friends" rows="5" cols="5" bypass="cancel" target="_top" /> </fb:request-form> </script> </fb:serverfbml> <div id="fb-root"></div> <script> window.fbAsyncInit = function () { FB.init({ appId: 'xxxxxxx', status: true, cookie: true, xfbml: true }); }; (function () { var e = document.createElement('script'); e.async = true; e.src = document.location.protocol + '//connect.facebook.net/en_US/all.js'; document.getElementById('fb-root').appendChild(e); } ()); </script> Can someone give me a working example using new javascript API with a multi-friend-selector?

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  • make emacs in a terminal use dark colors and not light font-lock colors

    - by vy32
    I am using emacs on MacOS 10.6 with Terminal. I have a white background. It's very hard to read quoted C++ strings. They are coming up in pale green. Keywords are in turquoise. After searching through the source I cam across cpp.el and have determined that I am using the cpp-face-light-name-list instead of cpp-face-dark-name-list. Apparently this function is supposed to chose the correct list based on the background color: (defcustom cpp-face-default-list nil "Alist of faces you can choose from for cpp conditionals. Each element has the form (STRING . FACE), where STRING serves as a name (for `cpp-highlight-buffer' only) and FACE is either a face (a symbol) or a cons cell (background-color . COLOR)." :type '(repeat (cons string (choice face (cons (const background-color) string)))) :group 'cpp) But it doesn't seem to be working. What should I put in my .emacs file so that I get the cpp-face-dark-list instead of cpp-face-light-list? Thanks!

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  • Flex vs. jQuery vs. GWTvs./ Closre vs. Cappuccino vs. plain JS and HTML5?

    - by Laith J
    Hello, I'm creating my first web application and I'm really confused as to what technology to go for. My application needs to look serious (like an application), it doesn't need many colorful graphical interfaces. It only needs a toolbar, a tab bar, a split panel (preferably 3 columns), an easily-formatable text field, and a status bar. It will connect to a MySQL database through PHP (unless I go for GWT). Users will upload files. My evaluation of the options: Flex: Probably the easiest to develop but I'm pretty sure my application is something one would use on an iPad and with Flash's future on the iPad still unsure, I don't want to take the risk, otherwise Flex would've been my choice. jQuery: I've heard a lot about it and a lot of people recommend but I don't know how easy it is to use and how customizable the look of my app is. GWT: The problem with GWT is that it doesn't have many widgets. Another problem is that I'm gonna have to host the files in AppEngine's datastore and transfer them back and forth to a web server that will do operations on them (I need to process them) which adds more traffic and slows the process which worsens the user experience. Closure: It has a nice toolbar and a nice text field. I'm not sure how easy it is to use. Plus, I read an article that makes it sound really bad. Cappuccino: It has a very nice UI and it has a mac feel. I'm planning to give my application a mac feel anyway so this will save me a lot of theming. But if I go for this option I won't be able to make use of HTML5's new features (especially working offline). Plain JS and HTML5: This gives me the most flexibility but it is the hardest to work for. I'm sorry if this is subjective but I really need help with this.

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  • WCF net.tcp bindings, message formats and security questions

    - by RemotecUk
    Hi, sorry for the stupid questions but there are just some things about WCF I cant get my head around. Would be greatful for some advice on the following.... At a very basic level is it correct that WCF uses either Binary (Net.Tcp), HTTP or MSMQ to transfer my message on the wire? However is it true that in all cases, regardless of how the data is transferred the message itself in in the SOAP format with headers and a body? So its a sort of XML message that is transmitted in either HTTP/S or in a binary format. Is Net.Tcp a good choice for my client server app - its similar to a messenger app in that the clients are all remote users on the other side of the firewall to my server. Most things I am reading are telling to use WS* and HTTP. Is Net.Tcp secured by standard and without certificates? - that is - people cannot listen on the wire and decode the data thats going to and from. Is it possible to send a username and password using net.tcp and without an installed certificate? If so I presume I can hook this up to my membership provider and authenticate access to each method on my service contract implementation. I presume that with username and password security, the proxy is initialised with the username and password and that this information is is sent with every request. Then my membership provider will be invoked for each method call and do whatever it needs to do to get the authorisation for the method. Sorry for the dump of questions but would be great to know if Im thinking the right way about how WCF works. Thanks.

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  • Sparse parameter selection using Genetic Algorithm

    - by bgbg
    Hello, I'm facing a parameter selection problem, which I would like to solve using Genetic Algorithm (GA). I'm supposed to select not more than 4 parameters out of 3000 possible ones. Using the binary chromosome representation seems like a natural choice. The evaluation function punishes too many "selected" attributes and if the number of attributes is acceptable, it then evaluates the selection. The problem is that in these sparse conditions the GA can hardly improve the population. Neither the average fitness cost, nor the fitness of the "worst" individual improves over the generations. All I see is slight (even tiny) improvement in the score of the best individual, which, I suppose, is a result of random sampling. Encoding the problem using indices of the parameters doesn't work either. This is most probably, due to the fact that the chromosomes are directional, while the selection problem isn't (i.e. chromosomes [1, 2, 3, 4]; [4, 3, 2, 1]; [3, 2, 4, 1] etc. are identical) What problem representation would you suggest? P.S If this matters, I use PyEvolve.

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  • Visual Studio setup problem - 'A problem has been encountered while loading the setup components. Ca

    - by kronoz
    Hi All, I've had a serious issue with my Visual Studio 2008 setup. I receive the ever-so-useful error 'A problem has been encountered while loading the setup components. Canceling setup.' whenever I try to uninstall, reinstall or repair Visual Studio 2008 (team system version). If I can't resolve this issue I have no choice but to completely wipe my computer and start again which will take all day long! I've recently received very strange errors when trying to build projects regarding components running out of memory (despite having ~2gb physical memory free at the time) which has rendered my current VS install useless. Note I installed VS2005 shell version using the vs_setup.msi file in the SQL Server folder after I had installed VS2008, in order to gain access to the SQL Server 2005 Reporting Services designer in Business Intelligence Development Studio (this is inexplicably unavailable in VS2008). Does anyone have any solutions to this problem? P.S.: I know this isn't directly related to programming, however I feel this is appropriate to SO as it is directly related to my ability to program at all! Note: A colleague found a solution to this problem, hopefully this should help others with this problem.

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  • Enterprise SSO & Identity management / recommendations

    - by Maxim Veksler
    Hello Friends, We've discussed SSO before. I would like to re-enhance the conversation with defined requirements, taking into consideration recent new developments. In the past week I've been doing market research looking for answers to the following key issues: The project should should be: Requirements SSO solution for web applications. Integrates into existing developed products. has Policy based password security (Length, Complexity, Duration and co) Security Policy can be managed using a web interface. Customizable user interface (the password prompt and co. screens). Highly available (99.9%) Scalable. Runs on Red Hat Linux. Nice to have Contains user Groups & Roles. Written in Java. Free Software (open source) solution. None of the solutions came up so far are "killer choice" which leads me to think I will be tooling several projects (OWASP, AcegiSecurity + X??) hence this discussion. We are ISV delivering front-end & backend application suite. The frontend is broken into several modules which should act as autonomous unit, from client point of view he uses the "application" - which leads to this discussion regrading SSO. I would appreciate people sharing their experience & ideas regarding the appropriete solutions. Some solutions are interesting CAS Sun OpenSSO Enterprise JBoss Identity IDM JOSSO Tivoli Access Manager for Enterprise Single Sign-On Or more generally speaking this list Thank you, Maxim.

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  • How to parse SOAP response from ruby client?

    - by Richard O'Neil
    Hi I am learning Ruby and I have written the following code to find out how to consume SOAP services: require 'soap/wsdlDriver' wsdl="http://www.abundanttech.com/webservices/deadoralive/deadoralive.wsdl" service=SOAP::WSDLDriverFactory.new(wsdl).create_rpc_driver weather=service.getTodaysBirthdays('1/26/2010') The response that I get back is: #<SOAP::Mapping::Object:0x80ac3714 {http://www.abundanttech.com/webservices/deadoralive} getTodaysBirthdaysResult=#<SOAP::Mapping::Object:0x80ac34a8 {http://www.w3.org/2001/XMLSchema}schema=#<SOAP::Mapping::Object:0x80ac3214 {http://www.w3.org/2001/XMLSchema}element=#<SOAP::Mapping::Object:0x80ac2f6c {http://www.w3.org/2001/XMLSchema}complexType=#<SOAP::Mapping::Object:0x80ac2cc4 {http://www.w3.org/2001/XMLSchema}choice=#<SOAP::Mapping::Object:0x80ac2a1c {http://www.w3.org/2001/XMLSchema}element=#<SOAP::Mapping::Object:0x80ac2774 {http://www.w3.org/2001/XMLSchema}complexType=#<SOAP::Mapping::Object:0x80ac24cc {http://www.w3.org/2001/XMLSchema}sequence=#<SOAP::Mapping::Object:0x80ac2224 {http://www.w3.org/2001/XMLSchema}element=[#<SOAP::Mapping::Object:0x80ac1f7c>, #<SOAP::Mapping::Object:0x80ac13ec>, #<SOAP::Mapping::Object:0x80ac0a28>, #<SOAP::Mapping::Object:0x80ac0078>, #<SOAP::Mapping::Object:0x80abf6c8>, #<SOAP::Mapping::Object:0x80abed18>] >>>>>>> {urn:schemas-microsoft-com:xml-diffgram-v1}diffgram=#<SOAP::Mapping::Object:0x80abe6c4 {}NewDataSet=#<SOAP::Mapping::Object:0x80ac1220 {}Table=[#<SOAP::Mapping::Object:0x80ac75e4 {}FullName="Cully, Zara" {}BirthDate="01/26/1892" {}DeathDate="02/28/1979" {}Age="(87)" {}KnownFor="The Jeffersons" {}DeadOrAlive="Dead">, #<SOAP::Mapping::Object:0x80b778f4 {}FullName="Feiffer, Jules" {}BirthDate="01/26/1929" {}DeathDate=#<SOAP::Mapping::Object:0x80c7eaf4> {}Age="81" {}KnownFor="Cartoonists" {}DeadOrAlive="Alive">]>>>> I am having a great deal of difficulty figuring out how to parse and show the returned information in a nice table, or even just how to loop through the records and have access to each element (ie. FullName,Age,etc). I went through the whole "getTodaysBirthdaysResult.methods - Object.new.methods" and kept working down to try and work out how to access the elements, but then I get to the array and I got lost. Any help that can be offered would be appreciated.

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  • UML class diagram vs ER database diagram

    - by salva84
    Hi, I'm a little confused, I'm developing a program, the program consist in two parts, the server and the clients, there are groups, places, messages... stored in the server, and the clients has to connect with it. I've design the use cases diagram, the activity diagrams, and I have design the class diagram too. The thing is that I want to implement the server in a mysql tables for storing the users, groups, places... users in groups... so I've designed a E-R diagram consisting in 6 tables, but the problem is that I think that my class diagram and my ER diagram looks too similar, I mean, I think I'm not doing things right because I have a class for each table practically, and when I have to extract all the users on my system, do I have to convert all the rows into objects at first and write in the database for each object modified? The easy choice for me would be to base my whole application only in the database, and making a class to extract and insert data in it, but I have to follow the UML specification and I'm a little confused what to do with the class diagram, because the books I have read say that I have to create a class for each "entity" of my program. Sorry for my bad English. Thank you.

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  • When am I ready for contracting work?

    - by Kirk Broadhurst
    What skills are required to work on a temp / contracting basis, and how does a developer know when they are ready to work in these circumstances? I have some colleagues who are suggesting contracting work is 'the way to go'; the pay is significantly better. It appears that when a permanent position pays (X times $10k) per year, the corresponding contract position pays almost $X per hour - which is close to twice as much. I look forward to doing this type of work as an experienced expert, but worry that by doing so right now I'd be turning away learning and development opportunities. My assumptions about contract work are the following: less / zero money invested on training and development less concern for job satisfaction and learning ("they won't be here in 12 months") possibly less concern about the overall quality of the project ("we won't be here in 12 months") There are similar questions on stack overflow at the moment but what I've really looking for is: What does the developer give up by moving to contract work? Is it preferable to have structured learning in a permanent position rather than seat-of-the-pants learning in a contract position? What skill leve should the contractor have before making the move? Is there still the same kind of growth in contracting that there is in permanent positions? Rightly or wrongly, I see this as a choice between $ (contracting) and learning / development (permanent). Is this fair?

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  • Large number of simultaneous long-running operations in Qt

    - by Hostile Fork
    I have some long-running operations that number in the hundreds. At the moment they are each on their own thread. My main goal in using threads is not to speed these operations up. The more important thing in this case is that they appear to run simultaneously. I'm aware of cooperative multitasking and fibers. However, I'm trying to avoid anything that would require touching the code in the operations, e.g. peppering them with things like yieldToScheduler(). I also don't want to prescribe that these routines be stylized to be coded to emit queues of bite-sized task items...I want to treat them as black boxes. For the moment I can live with these downsides: Maximum # of threads tend to be O(1000) Cost per thread is O(1MB) To address the bad cache performance due to context-switches, I did have the idea of a timer which would juggle the priorities such that only idealThreadCount() threads were ever at Normal priority, with all the rest set to Idle. This would let me widen the timeslices, which would mean fewer context switches and still be okay for my purposes. Question #1: Is that a good idea at all? One certain downside is it won't work on Linux (docs say no QThread::setPriority() there). Question #2: Any other ideas or approaches? Is QtConcurrent thinking about this scenario? (Some related reading: how-many-threads-does-it-take-to-make-them-a-bad-choice, many-threads-or-as-few-threads-as-possible, maximum-number-of-threads-per-process-in-linux)

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  • CakePHP, CodeIgniter or Rails for multi-user Tumblr clone?

    - by Jordan
    I'm about to start building a tumblr clone that handles multiple users (so premade clones like Gelato won't cut it) and I'm not sure which framework I'd like to build this is. Right now, I'm only intending to build a prototype. Something I can get a dozen friends on to test the concept and grow to maybe a couple hundred users to prove the market, so I'm not worried about long term scale. My biggest concern right now is quick deployment. I'd like to get from zero to signups in as short a time as possible, with as little customization to the framework of choice as possible. I have experience with PHP, but not Ruby. However, I don't think the learning curve would be too steep so I'm not ruling out rails. I just want the framework that is most appropriate for a system like a multi-user tumblr clone so that I can build it with as little hassle, and as quickly, as possible. If anyone has experience with a similar project, or with these frameworks and can offer an insightful perspective, I'd be very appreciative. Thanks for taking the time to read. Cheers, ~Jordan Feldstein

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  • Binary to strings as binary? C #/.NET

    - by acidzombie24
    Redis keys are binary safe. I'd like to mess around and put binary into redis using C#. My client of choice doesn't support writing binary keys it uses keys and it make sense. However i am just fooling around so tell me how i can do this. How do i convert a raw byte[] into a string? At first i was thinking about converting a byte[] to a utf8 string however unicode has some checks to see if its valid or not. So raw binary should fail. Actually i tried it out. Instead of failing i got a strange result. My main question is how do i convert a raw byte[] to the equivalent string? My unimportant question is why did i get a 512 byte string instead of an exception saying this is not a valid UTF8 string? code var rainbow = new byte[256]; for (int i = 0; i < 256; i++) { rainbow[i] = (byte)i; } var sz = Encoding.UTF8.GetString(rainbow); var szarr = Encoding.UTF8.GetBytes(sz); Console.WriteLine("{0} {1} {2}", ByteArraysEqual(szarr, rainbow), szarr.Length, rainbow.Length); Output False 512 256

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  • Computer science final year project ideas

    - by roul
    I'm a Computer Science undergraduate student in UK and should be deciding the subject of my final year project soon. The school is pretty flexible with the subject... "The topic can be any area of the subject which is of mutual interest to both the student and supervisor. Topics can range from purely theoretical studies to practical work building a system for some third party, although most projects aim to provide a balance between the theoretical and practical aspects of the subject." ...so I'm a bit lost since I want to do something in software engineering but have no idea what (subject) or with what (languages)! :) a) Languages: I've had experience with Java, C# and ASP.NET mostly but I would definitely be interested in learning new languages/frameworks. I'm kind of drawn by the idea of dynamic languages at the moment so IronPython seems likely. b) Subject: Anything that will keep me interested through the year and will give me the opportunity to learn a lot of stuff. Maybe something that has to do with music, or a fancy website, or a website about music :P anything really. Open to any thoughts/ideas, geeky or cool! Edit: Professors do usually supervise projects in their research areas but I currently have the choice to approach any of them according to my interest - whatever that is.

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  • NPTL Default Stack Size Problem

    - by eyazici
    Hello, I am developing a multithread modular application using C programming language and NPTL 2.6. For each plugin, a POSIX thread is created. The problem is each thread has its own stack area, since default stack size depends on user's choice, this may results in huge memory consumption in some cases. To prevent unnecessary memory usage I used something similar to this to change stack size before creating each thread: pthread_attr_t attr; pthread_attr_init (&attr); pthread_attr_getstacksize(&attr, &st1); if(pthread_attr_setstacksize (&attr, MODULE_THREAD_SIZE) != 0) perror("Stack ERR"); pthread_attr_getstacksize(&attr, &st2); printf("OLD:%d, NEW:%d - MIN: %d\n", st1, st2, PTHREAD_STACK_MIN); pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED); /* "this" is static data structure that stores plugin related data */ pthread_create(&this->runner, &attr, (void *)(void *)this->run, NULL); EDIT I: pthread_create() section added. This did not work work as I expected, the stack size reported by pthread_attr_getstacksize() is changed but total memory usage of the application (from ps/top/pmap output) did not changed: OLD:10485760, NEW:65536 - MIN: 16384 When I use ulimit -s MY_STACK_SIZE_LIMIT before starting application I achieve the expected result. My questions are: 1-) Is there any portable(between UNIX variants) way to change (default)thread stack size after starting application(before creating thread of course)? 2-) Is it possible to use same stack area for every thread? 3-) Is it possible completely disable stack for threads without much pain?

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  • Worse is better. Is there an example?

    - by J.F. Sebastian
    Is there a widely-used algorithm that has time complexity worse than that of another known algorithm but it is a better choice in all practical situations (worse complexity but better otherwise)? An acceptable answer might be in a form: There are algorithms A and B that have O(N**2) and O(N) time complexity correspondingly, but B has such a big constant that it has no advantages over A for inputs less then a number of atoms in the Universe. Examples highlights from the answers: Simplex algorithm -- worst-case is exponential time -- vs. known polynomial-time algorithms for convex optimization problems. A naive median of medians algorithm -- worst-case O(N**2) vs. known O(N) algorithm. Backtracking regex engines -- worst-case exponential vs. O(N) Thompson NFA -based engines. All these examples exploit worst-case vs. average scenarios. Are there examples that do not rely on the difference between the worst case vs. average case scenario? Related: The Rise of ``Worse is Better''. (For the purpose of this question the "Worse is Better" phrase is used in a narrower (namely -- algorithmic time-complexity) sense than in the article) Python's Design Philosophy: The ABC group strived for perfection. For example, they used tree-based data structure algorithms that were proven to be optimal for asymptotically large collections (but were not so great for small collections). This example would be the answer if there were no computers capable of storing these large collections (in other words large is not large enough in this case). Coppersmith–Winograd algorithm for square matrix multiplication is a good example (it is the fastest (2008) but it is inferior to worse algorithms). Any others? From the wikipedia article: "It is not used in practice because it only provides an advantage for matrices so large that they cannot be processed by modern hardware (Robinson 2005)."

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  • Java EE suitablity for a social network using Cassandra datastore ??

    - by Marcos
    We are in the process of making some important technology decisions for a social networking application. We're planning to have Cassandra(a NoSQL database to support efficient data storage). We would be using Hector(a Java client) to interact with Cassandra. 1.) Would Java EE be a good choice over PHP for a social networking application in terms of performance, scalabilty & complexities? 2.) Another possible implementation strategy, Is it suitable to have backend alone in Java and rest in PHP? 3.) What differences(as compared to PHP) it makes in terms of costs at various stages of application development, deployment and maintenance ? 4.) What are the things to keep in mind as we move along with Java development& deployment(as we are relatively new to the Java background) ? 5.) If you could list some major production deployments of similar type(social network) applications in Java. Thank you!

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  • Decisions in teaching someone else to program: language selection

    - by Dinah
    My friend would like for me to guide her into learning programming. She's already proven enormous aptitude for thinking like a programmer but is scared of the idea of programming since in her mind it's relegated to some magical realm accessible only to smart people and trained computer scientists (ironically, I am neither but that's beside the point). My main question is the age-old and irritating question: which language should I chose? I've limited it down to these: PHP: dead simple to start with and I remember enough of the language to answer all novice questions. However, I can think of a million reasons why I wouldn't recommend this as a first language. The most diplomatic of which is that there's no desktop app option to which I would feel comfortable subjecting a novice. Python: supposed to be wonderful for beginners and generally everything I've heard about it screams that this is the correct choice. That's the problem: everything I've heard about it. I don't know it yet and have a lot of projects going on right now so I don't feel like learning it yet -- but I'm going to be the tech-support when any little thing goes wrong. I know there are tons of online resources but in the frustration of the moment, it's always going to be just me. C#: this is the language I'm most comfortable with so I know I can be good tech support. I also love this language and its versatility and community. The big drawback here is that I remember when I first learned it after doing mainly PHP, Perl, and JavaScript and I found the experience overwhelming. You are simultaneously learning: programming concepts, C# syntax, strong typing, OOP, and a complex powerful IDE with a bazillion options and buttons all over it.

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  • When should one use the following: Amazon EC2, Google App Engine, Microsoft Azure and Salesforce.com

    - by vicky21
    I am asking this in very general sense. Both from cloud provider and cloud consumer's perspective. Also the question is not for any specific kind of application (in fact the intention is to know which type of applications/domains can fit into which of the cloud slab -SaaS PaaS IaaS). My understanding so far is: IaaS: Raw Hardware (Processors, Networks, Storage). PaaS: OS, System Softwares, Development Framework, Virtual Machines. SaaS: Software Applications. It would be great if Stackoverflower's can share their understanding and experiences of cloud computing concept. EDIT: Ok, I will put it in more specific way - Amazon EC2: You don't have control over hardware layer. But you can take your choice of OS image, Dev Framework (.NET, J2EE, LAMP) and Application and put it on EC2 hardware. Can you deploy an applications built with Google App Engine or Azure on EC2? Google App Engine: You don't have control over hardware and OS and you get a specific Dev Framework to build your application. Can you take any existing Java or Python application and port it to GAE? Or vice versa, can applications that were built on GAE be taken out of GAE and ported to any Application Server like Websphere or Weblogic? Azure: You don't have control over hardware and OS and you get a specific Dev Framework to build your application. Can you take any existing .NET application and port it to Azure? Or vice versa, can applications that were built on Azure be taken out of Azure and ported to any Application Server like Biztalk?

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  • Wrong item checked when filtering ListView in android

    - by aspartame
    I have a ListView with multiple choice entries where some are checked from the beginning using setItemChecked(position, true); I combine this with the filtering option setTextFilterEnabled(true) so it's easy to find a specific entry in the list. The problem is that when I filter the list the entries switch position in the list view. Take for example three entries: 'A', 'B' and 'C' where 'C' is checked beforehand (i.e. the entry at position 3 in the list). When I type a 'C' on the keyboard, only the 'C' entry is displayed (as intended). Now 'C' is not checked anymore, since the entry has moved from the checked position 3 to the unchecked position 1 in the list. This behavior leads to some not very welcome effects in the app. Is there a way to "move the selection with the filtering", i.e. bind the checked state to the entry and not to its initial position in the list? Or do I need to find a new approach? Thanks, Linus

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  • Nested dereferencing arrows in Perl: to omit or not to omit?

    - by DVK
    In Perl, when you have a nested data structure, it is permissible to omit de-referencing arrows to 2d and more level of nesting. In other words, the following two syntaxes are identical: my $hash_ref = { 1 => [ 11, 12, 13 ], 3 => [31, 32] }; my $elem1 = $hash_ref->{1}->[1]; my $elem2 = $hash_ref->{1}[1]; # exactly the same as above Now, my question is, is there a good reason to choose one style over the other? It seems to be a popular bone of stylistic contention (Just on SO, I accidentally bumped into this and this in the space of 5 minutes). So far, none of the usual suspects says anything definitive: perldoc merely says "you are free to omit the pointer dereferencing arrow". Conway's "Perl Best Practices" says "whenever possible, dereference with arrows", but it appears to only apply to the context of dereferencing the main reference, not optional arrows on 2d level of nested data structures. "MAstering Perl for Bioinfirmatics" author James Tisdall doesn't give very solid preference either: "The sharp-witted reader may have noticed that we seem to be omitting arrow operators between array subscripts. (After all, these are anonymous arrays of anonymous arrays of anonymous arrays, etc., so shouldn't they be written [$array-[$i]-[$j]-[$k]?) Perl allows this; only the arrow operator between the variable name and the first array subscript is required. It make things easier on the eyes and helps avoid carpal tunnel syndrome. On the other hand, you may prefer to keep the dereferencing arrows in place, to make it clear you are dealing with references. Your choice." Personally, i'm on the side of "always put arrows in, since itg's more readable and obvious tiy're dealing with a reference".

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